The present disclosure relates to an image processing apparatus and an image processing method.
The standardization of an image coding scheme called HEVC (High Efficiency Video Coding) by JCTVC (Joint Collaboration Team-Video Coding), which is a joint standardization organization of ITU-T and ISO/IEC, is currently under way for the purpose of improving coding efficiency more than H.264/AVC (see, for example, “High Efficiency Video Coding (HEVC) text specification draft 10 (for FDIS & Consent)” by Benjamin Bross, Woo-Jin Han, Gary J. Sullivan, Jens-Rainer Ohm, Gary J. Sullivan, Ye-Kui Wang, and Thomas Wiegand, (JCTVC-L1003 v 4, Jan. 14 to 23, 2013).
HEVC provides not only coding of a single layer but also scalable video coding, as in known image coding schemes such as MPEG2 and AVC (Advanced Video Coding). An HEVC scalable video coding technology is also called SHVC (Scalable HEVC) (for example, see “Description of scalable video coding technology proposal by Qualcomm (configuration 2)” by Jianle Chen, el. al, (JCTVC-K0036, Oct. 10 to 19, 2012).
Incidentally, scalable video coding is generally a technology that hierarchically encodes a layer transmitting a rough image signal and a layer transmitting a fine image signal. Typical attributes hierarchized in the scalable video coding mainly include the following three:                Space scalability: Spatial resolutions or image sizes are hierarchized.        Time scalability: Frame rates are hierarchized.        SNR (Signal to Noise Ratio) scalability: SN ratios are hierarchized.        
Further, though not yet adopted in the standard, the bit depth scalability and chroma format scalability are also discussed.
In “SCE4: Results on 5.3-test1 and 5.3-test2” by Philippe Bordes, et al., (JCTVC-O0159, Oct. 23 to Nov. 1, 2013) and “Non-SCE4/AHG14: Combined bit-depth and color gamut conversion with 3D LUT for SHVC color gamut scalability” by Yuwen He, et al., (JCTVC-O0161, Oct. 23 to Nov. 1, 2013), color gamut scalability in which color gamuts were hierarchized was proposed. For example, in high definition (HD) televisions, an image size of 1920×1080 pixels, a color gamut of ITU-R BT.709, and a bit depth of 8 bits are generally used. On the other hand, in ultra high definition (UHD) televisions, use of an image size of 4000×2000 pixels or 8000×4000 pixels, a color gamut of ITU-R BT.2020, and a bit depth of 10 or 12 bits is being investigated. According to methods described in “SCE4: Results on 5.3-test1 and 5.3-test2” by Philippe Bordes, et al., (JCTVC-O0159, Oct. 23 to Nov. 1, 2013) and “Non-SCE4/AHG14: Combined bit-depth and color gamut conversion with 3D LUT for SHVC color gamut scalability” by Yuwen He, et al., (JCTVC-O0161, Oct. 23 to Nov. 1, 2013), corresponding pixel vectors in the color gamut of BT.2020 are predicted using a 3-dimensional lookup table from pixel vectors (Y, U, V) in the color gamut of BT.709.